1. Field of the Invention
The present invention relates to driving circuitry and to an integrated circuit usable in such driving circuitry and its control.
2. Description of the Related Art
An electronic apparatus such as an inkjet recording apparatus includes a plurality of motors, for example, a scanning motor for a recording head and a conveying motor for a recording paper. Some motor driving circuits for driving a plurality of motors are formed as one integrated circuit (IC). Further, there is a direct current/direct current (DC/DC) converter for supplying electric power to a motor, a recording head, a control circuit or the like. Japanese Patent Application Laid-Open No. 2006-20495 discusses one integrated circuit in which a DC/DC converter circuit and a motor driving circuit are integrated.
A DC/DC converter circuit provided on an integrated circuit converts an input voltage to a lower output voltage. In some central processing units (CPUs) and application-specific integrated circuits (ASICs) in recent years, a driving voltage is reduced. Thus, a voltage to be output to a low voltage circuit is also reduced. Under such circumstances, a difference between an input voltage and an output voltage is increased. Accordingly, in a DC/DC converter circuit, the amount of heat generated due to conversion loss of a voltage is increased. The heating amount in an integrated circuit including a motor driving circuit causes malfunction of a driving circuit. Further, a control unit of an electronic apparatus uses electric power generated in an integrated circuit. Thus, heat generated in an integrated circuit causes operation of a DC/DC converter circuit to stop and as a result, operation of an electronic apparatus is discontinued.